This invention relates to signal transmission method and system in elevator equipment and more particularly to signal transmission method and system suitable for transmission of signals to respective elevator halls and to the cage.
Conventionally, information about respective floors in elevator equipment, for example, information about an elevator hall call button and associated response lamp and an indicator for displaying a cage position is transmitted through a necessary number of transmission lines which are laid to extend from an elevator controller (sometimes simply called a controller) installed in a machine room. In such a system, the number of transmission lines required for transmission of information about hall call buttons and associated response lamps, and indicators in elevator equipment for, for example, only eight floors amounts to 43. That is, the number of transmission lines necessary for hall call buttons and associated response lamps measures [6 (representative of the number of intermediate floors).times.4+2 (representative of the number of end floors).times.2+1 (common)], the number of transmission lines necessary for indicators measures [2 (representative of the number of direction lamps)+8 (representative of the number of floors) +1 (common)], and the number of transmission lines necessary for signal lamps measures [2+1 (common)], thus totaling to 43. This accounts for the fact that a great number of wiring conductors are needed for transmission of signals to respective floors and as the number of stories of building increases and the function of elevator equipment advances, the interface of the controller faces serious problems in its standardization, installation and maintenance.
To solve these problems, JP-A-61-69677 and JP-A-61-194943 propose a countermeasure in which a main station or a master comprised of a microcomputer is provided in the controller, and a remote station or a slave comprised of a microcomputer is installed on each floor, whereby serial transmission is effected with a view of reducing the number of wiring conductors. This proposal can reduce the number of wiring conductors to a great extent and standardize the interface of the controller.
In the prior art, however, the respective floors are first designated and transmission/reception of information including information common to all of the floors (common information) and information unique to the respective floors (unique information) is carried out in unit of floor, with the result that the common information is transmitted repetitively and timing for turning on the response lamp and the like is inevitably retarded. Since the response lamp in elevator equipment must be turned on within a predetermined interval of time (for example, 0.1 second) following depression of the call button in order for the operator or user not to recognize a retarded response, all of information necessary for the respective floors must be transmitted and received at very high transmission speeds through the complete serial transmission. This will impose great constraint on the system when the number of floors is very large.
Preferably, the elevator equipment is very immune to environmental noise and from this point of view, transmission at a relatively low speed is more desirable than transmission at a very high speed which is sensitive to the noise.
As the function of the elevator equipment advances, in addition to transmission of information about hall call button which is necessary for elevator control, transmission of desired information other than the information for elevator control including traffic information, weather forecast, time information services, visual information and guidance to entertainments being held in building is desired to be performed between each floor and the controller. The prior art does not take such a demand into consideration. Accordingly, when the information transmission has a low transmission speed, there arise problems that the response time is retarded and that the desired information other than that for elevator control can not be transmitted.
Further, the prior art never fails to consider to procedure for accurate exchange of information between the main station or master and each remote station or slave but in the prior art, information received through normal procedure is not checked for its rationality and there is a possiblity that, for example, such an erroneous operation as turn-on of the response lamp takes place even when the call butoon is not depressed. Presumably, the erroneous operation is due to noises generated from nearly power cables, inductive loads or on-off contacts. When interfered with the noises, inconsistencies occur in the information, giving a feeling of uncomfortable elevator riding and causing invalidation of running.
Known references relevant to the present invention will be commented herein. The aforementioned JP-A-61-69677 uses a microprocessor in either of the elevator controller and the apparatus at each elevator stop to permit the two microprocessors to be interconnected together through the serial transmission line but fails to refer to transmission of the unique information and common information.
The aforementioned JP-A-61-194943 describes that a main station installed in the elevator controller is connected to remote stations installed on respective floors or a remote station carried on the cage by a transmission line of bus mode. In this literature, transmission/reception of information is carried out separately between the main station and each remote station. However, like JP-A-61-69677, this reference neither discloses sorting of information into the unique information and common information nor refers to the common information and unique information.
JP-A-55-16829 disclosed by reference herein describes that the elevator controller is connected to the cage by a serial transmission line but in no way describes the connection between the apparatus at elevator stop on each floor and the elevator controller.
JP-A-62-4179 (corresponding to U.S. Pat. No. 4,709,788) disclosed by reference herein describes that a plurality of main stations are provided, remote stations installed on respective floors are connected to the plural main stations through a serial transmission line (bus), and the respective main stations are assigned with the right to control bus with priority, whereby when a main station is not permitted to transmit information, a different main station which is the second to have the right to control bus is then permitted to transmit information, thereby permitting continuity of normal running of the cage. This reference, like JP-A-61-194943, never refers to the common information.